Oil and fat compositions having antifoaming effect

ABSTRACT

Oil and fat compositions containing at least 0.01% by mass of one or more polyglycerol fatty acid esters having an average degree of polymerization of 6 to 30 and an average degree of substitution of 4 to 32 have an antifoaming effect and they are usable as general-purpose oil and fat compositions having controlled foaming properties in the course of the frying, good cooking properties and a long deep-frying life.

This application is a continuation of International Application No.PCT/JP01/07266 filed on Aug. 24, 2001, the entire content of which ishereby incorporated by reference.

This application claims priority under 35 U.S.C. §§119 and/or 365 to2000-258084 and 2000-274398 filed in Japan on Aug. 28, 2000 and Sep. 11,2000; the entire content of which is hereby incorporated by reference.

BACKGROUND OF THE INVENTION

The present invention relates to oil and fat compositions used asgeneral-purpose cooking oils. In particular, the present inventionrelates to oil and fat compositions containing polyglycerol fatty acidesters, having a high suitability for cooking and exhibiting anexcellent antifoaming effect while they are used for cooking.

As heat-cooking oils and fats for deep-frying and stir-frying, therehave been used soybean oil, rapeseed oil, corn oil, cotton seed oil,rice bran oil, safflower oil, sunflower oil, sesame oil, olive oil,coconut oil, palm oil, lard and modified oils (transesterified oils andhydrogenated oils) prepared from them alone or in the form of a mixtureof two or more of them.

In deep-frying in an oil or fat, a vapor is usually formed from amaterial being fried and, as a result, foams are formed. While thefrying is repeated, the oil or fat is deteriorated and the foamingthereof is accelerated by an influence of ingredients eluted from thematerials in the course of the deep-frying. When the foaming is serious,the materials are hidden by the foams and they cannot be seen, and thefoams overflow from the pan to make the cooking operation dangerous.Accordingly, the amount of the material that can be deep-fried in theoil is limited. Particularly when the material to be deep-fried containseggs or meats, the oil or fat is rapidly deteriorated. For controllingthe foaming of the oil in the course of the deep-frying, a silicone oilhas been added to the oil. However, the use of the silicone oil isrecently avoided because the effect thereof is limited and thebiodegradability thereof is only low.

A mixed oil of coconut oil and soybean oil and a transesterified oilprepared from medium length fatty acid triglycerides and rapeseed oilfoam relatively easily to form a large quantity of the foams. Thefoaming of triglycerides comprising both fatty acids having 6 to 12carbon atoms and fatty acids having 14 to 22 carbon atoms cannot becontrolled even by the addition of the silicone.

DISCLOSURE OF THE INVENTION

The object of the present invention is to provide oil and fatcompositions used as general-purpose cooking oils having a longdeep-frying life, which compositions have a controlled foaming in thecourse of the frying and also good cooking properties.

After intensive investigations made for the purpose of attaining theabove-described object, the inventors have found that when a specifiedpolyglycerol fatty acid ester is incorporated in the oil and fatcompositions, it becomes easy to remove the foam and the cookingproperties of the compositions can be improved. The present inventionhas been completed on the basis of this finding.

Namely, the present invention relates to oil and fat compositions whichcomprises triglycerides as the main components and at least 0.01% bymass of one or more polyglycerol fatty acid esters having an averagedegree of polymerization of 6 to 30 and an average degree ofsubstitution of 4 to 32. In the present invention, the higher theunsaturated fatty acid content of the fatty acids constituting thepolyglycerol fatty acid esters, the better. The oil and fat compositionswherein fatty acids constituting the triglycerides are both those having6 to 12 carbon atoms and those having 14 to 22 carbon atoms arepreferred because the effects thereof are remarkable.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The oil and fat composition of the present invention containstriglycerides as the main components and also at least 0.01% by mass ofone or more polyglycerol fatty acid esters having an average degree ofpolymerization of 6 to 30 and an average degree of substitution of 4 to32. The term “main components” indicates that the triglyceride contentis at least 50% by mass. The oil and fat composition of the presentinvention has a triglyceride content of preferably 50 to 99.99% by mass,more preferably 50 to 99.9% by mass and particularly preferably at least90% by mass.

The glycerides mainly comprising triglycerides include oil and fatstarting materials such as ordinary edible oils, transesterified oils,glycerol esters and hydrolyzates of them. The raw materials of oils andfats include, for example, soybean oil, rapeseed oil, corn oil, sesameoil, sesame salad oil, perilla oil (Shiso-yu), linseed oil, peanut oil,safflower oil, safflower oil having a high oleic acid content, sunfloweroil, sunflower oil having a high oleic acid content, cotton seed oil,grapeseed oil, macadamia nut oil, hazelnut oil, pumpkin nut oil, walnutoil, camellia oil, tea seed oil, perilla oil (Egoma-yu), borage oil,olive oil, rice bran oil, wheat germ oil, palm oil, palm kernel oil,coconut oil, cacao butter, beef tallow, lard, chicken fat, mild fat,fish oil, seal oil, alga oil, medium length fatty acid triglycerides,these oils and fats having a saturation degree lowered by theimprovement in the quality, oils and fats obtained by the hydrogenationof them and fractionated oils and fats. The raw materials of oils andfats are not limited to them.

The polyglycerol fatty acid esters having an average degree ofpolymerization of 6 to 30 and an average degree of substitution of 4 to32 have an effective antifoaming effect. The polyglycerol fatty acidesters can be used either alone or in the form of a mixture of two ormore of them. Although diglycerol fatty acid esters having an averagedegree of polymerization of 2 also have the antifoaming effect, theeffect is less than that of the polyglycerol fatty acid esters of thepresent invention. Polyglycerol fatty acid esters having an averagedegree of polymerization of higher than 2 and lower than 6 and anaverage degree of polymerization of lower than 4 have no antifoamingeffect and, they sometimes have a contrary effect. They have a lowsolubility in fats and oils and the obtained solution is cloudy or aninsoluble matter deposits or precipitates therein in many cases. On thecontrary, the polyglycerol fatty acid esters having an average degree ofpolymerization of 6 to 30 and an average degree of substitution of 4 to32 have an effective antifoaming effect, and a high solubility in oilsand fats. Those having an average degree of polymerization of 9 to 25and an average degree of substitution of 5 to 27 are preferred, andthose having an average degree of polymerization of 11 to 20 and anaverage degree of substitution of 6 to 20 are more preferred.

The average degree of substitution is not higher than “average degree ofpolymerization +2”. For example, when the average degree ofpolymerization is 10, the average degree of substitution is not higherthan 12.

In the present invention, the term “average degree of polymerization ofpolyglycerol fatty acid esters” indicates the average degree ofpolymerization of the polyglycerols constituting the esters. The averagedegree of polymerization (n) of the polyglycerols is determined from themeasured hydroxyl group value (OHV) of the polyglycerols and thetheoretical value according to formula (3) given below. The hydroxylgroup value (OHV) of the polyglycerols is determined by the standardoil-and-fat analysis method. The average molecular weight (MW) isdetermined by the following formula (1):

MW=74n+18  (formula 1)

OHV=56110(n+2)/MW  (formula 2)

From formulae (1) and (2):

n=(112220−18×OHV)/(74×OHV−56110)  (formula 3)

In the present invention, the average degree of substitution isdetermined from the molar ratio of polyglycerols to fatty acidssubjected to the reaction for synthesizing the polyglycerol fatty acidesters. The molar ratio of compounds subjected to the reaction is theratio of the amount (mole) of the polyglycerols subjected to thereaction to the amount (mole) of the fatty acids subjected to thereaction, wherein the amount (mole) of the polyglycerols subjected tothe reaction is determined by dividing the mass (grams) of thepolyglycerols subjected to the reaction by the average molecular weight(MW) of the polyglycerols determined from the above-described,determined hydroxyl group value of the polyglycerols. For example, thepolyglycerol fatty acid esters of the present invention having anaverage degree polymerization of 15 and an average degree ofsubstitution of 8 have a measured hydroxyl group value of the chargedpolyglycerols of 846, and the average degree of polymerization (n) ofpolyglycerols is 15 and the average molecular weight (MW) of 1128according to the above-described formulae. After the synthesis by using1128 g (1 mol) of the polyglycerols and oleic acid (8 mols), the averagedegree of polymerization and the average degree of substitution aredetermined to be 15 and 8, respectively. In this case, thesaponification value and hydroxyl group value of the polyglycerol fattyacid esters are determined to be 130 to 160 and 130 to 160,respectively.

When the unsaturated fatty acid content of the total constituent fattyacids in the polyglycerol fatty acid esters is less than 50% by mass,the solubility of the esters in the oils and fats is often not as highas expected. In some cases, the obtained solution is cloudy or aninsoluble matter deposits or precipitates therein. Therefore,unsaturated fatty acid content of the total constituent fatty acids inthe polyglycerol fatty acid esters is preferably 50 to 100% by mass andmore preferably 70 to 100% by mass.

In the present invention, the term “constituent fatty acid content” is anumerical value obtained by methyl-esterifying or trimethyl-silylatingthe polyglycerol fatty acid esters and calculating it from the fattyacid composition analyzed by GLC (gas chromatography).

Generally, oils and fats containing medium length fatty acids, such asmixed oils of medium length fatty acid triglycerides and long chainfatty acid triglycerides, or transesterified oils of them, violentlymake foams. In such a case, the oil and fat composition of the presentinvention exhibits a remarkable effect and is suitably used. Namely, theconstituent fatty acids of the triglycerides preferably contain mediumlength fatty acids (6 to 12 carbon atoms). In particular, when theconstituent fatty acids of the triglycerides in the oil and fatcomposition include both fatty acids having 6 to 12 carbon atoms andfatty acids having 14 to 22 carbon atoms, the antifoaming effect of thepresent invention is remarkable. Thus, those fatty acids are preferred.In such a case, the remarkable effect can be obtained particularly whenthe ratio (% by mass) of the fatty acids having 6 to 12 carbon atoms tothe fatty acids having 14 to 22 carbon atoms is 5:95 to 95:5.

The polyglycerol fatty acid esters used in the present invention aregenerally obtained by the transesterification reaction of apolyglycerol, obtained by the dehydration condensation of glycerol orsynthesized from glycidol or epichlorohydrin, with a fatty acid.However, the method for synthesizing those polyglycerol fatty acidesters is not limited to this method.

The aliphatic carboxylic acids constituting the polyglycerol fatty acidesters are preferably saturated linear fatty acids, unsaturated linearfatty acids and organic acids each having 2 to 22 carbon atoms. Examplesof them include caproic acid, caprylic acid, capric acid, lauric acid,myristic acid, palmitic acid, stearic acid, arachidic acid, behenicacid, lignoceric acid, cerotic acid, palmitooleic acid, oleic acid,elaidic acid, linoleic acid, linolenic acid, eicosapentaenoic acid,docosahexaenoic acid, arachidonic acid, erucic acid, hydroxyfatty acids,ricinoleic acid, condensed ricinoleic acid, acetic acid and isobutyricacid. However, the aliphatic carboxylic acids are not limited to them.In these acids, fatty acids having 8 to 20 carbon atoms are preferredand those having 12 to 18 carbon atoms are more preferred.

The oil and fat composition of the present invention contains at least0.01% by mass, preferably 0.01 to 10% by mass and more preferably 0.1 to5% by mass, of the polyglycerol fatty acid esters. The oil and fatcomposition containing 0.1 to 3% by mass of the polyglycerol fatty acidesters has the best cooking properties.

The oil and fat composition of the present invention obtained asdescribed above is usable for the cooking as it is or after theincorporation of additives usually added to cooking oil and fatcompositions.

The additives are those used for the purposes of obtaining thesynergistic antifoaming effect, improving the storability, improving theoxidation stability, improving heat stability and inhibiting thecrystallization at a low temperature, such as polyglycerol fatty acidesters, sucrose fatty acid esters, glycerol fatty acid esters, sorbitanfatty acid esters, sorbitol fatty acid esters, vitamin E, ascorbic acidfatty acid esters, lignan, coenzyme Q, phospholipids, silicone oil andoryzanol; and also those used for the purposes of preventing adultdiseases, preventing diseases caused by life habits, controlling in vivooxidation and preventing adiposis, such as vitamin E, ascorbic acidfatty acid esters, lignan, coenzyme Q, phospholipids and oryzanol.

The cooking oil and fat composition of the present invention has aflavor and a taste equivalent or superior to those of ordinary vegetableoils available on the market, such as rapeseed oil, corn oil, saffloweroil and soybean oil. This composition is usable not only for makingstir-fried foods, deep-fried foods, marinades, etc. but also for makingfoods containing an oil or a fat, such as dressings, mayonnaise,margarine, confectioneries, cakes and drinks.

The following Examples will further illustrate the present invention,which by no means limit the invention.

EXAMPLES

<Preparation of Polyglycerol Fatty Acid Esters>

Glycerol was mixed with sodium hydroxide. The obtained mixture washeated to 90° C. and then dried under reduced pressure. The mixture wasthen heated at 200 to 270° C. and stirred to conduct the reaction. Afterthe completion of the reaction, the reaction mixture was filtered toobtain polyglycerols. The polyglycerols were various depending on thereaction temperature in the above-described range. Diglycerol (averagedegree of polymerization: 2) was obtained by the molecular distillationof the synthesized polyglycerols. Polyglycerols having an average degreeof polymerization of higher than 10 were obtained by GPC ofpolyglycerols having an average degree of polymerization of 10 to removethose having a low degree of polymerization. Various polyglycerolsobtained as described above were mixed with various fatty acids toconduct the reaction in the presence of sodium hydroxide as the catalystat 200° C. in nitrogen gas stream to obtain polyglycerol fatty acidesters (a to w). The polyglycerol fatty acid esters thus obtained areshown in Table 1 given below.

The average degree of polymerization and the average degree ofsubstitution were determined according to the above-describedcalculation formulae.

TABLE 1 Polyglycerol fatty acid esters Average degree Average degreeMain fatty acids (%) of polymerization of substitution C_(12:0) C_(14:0)C_(16:0) C_(18:0) C_(18:1) C_(18:2) a 2 1 30 15 45 10 b 4 1 9 6 80 5 c 44 31 69 d 5 6 9 6 80 5 e 6 5 9 6 80 5 f 8 8 28 25 41 6 g 9 6 9 6 80 5 h10 1 9 6 80 5 i 10 10 9 6 80 5 j 15 8 7 2 74 17 x 15 7 3 5 45 1 40 7 w10 9 34 3 2 4 51 6

Comparative Examples 1 to 12 and Examples 1 to 10

Comparative fat and oil compositions and the fat and oil compositions ofthe present invention shown in Tables 2 and 3 were prepared and theywere subjected to a foam-height test and a solubility test.

(Foam Height Tests)

20 g of each of oil and fat compositions was fed into a test tube(diameter: 25 mm, length: 200 mm) and heated to 160° C. with a blockheater (Dry Thermo Unit DTU-20 TAITEC CORPORATION). A potato cube havinga size of 1 cm×1 cm×1 cm was thrown into the composition, and thehighest height, from the oil surface level measured before the heating,of generated foams was taken as the foam height.

Evaluation:

≦40 mm: Antifoaming effect was recognized.

40<≦80 mm: Slight antifoaming effect was recognized.

>80 mm: Antifoaming effect was not recognized.

(Determination of Solubility)

100 g of each of the oil and fat compositions was fed into a 200 mlbeaker, heated to 50° C. and cooled to 30° C. Whether a clouding, milkyopaqueness or the formation of insoluble matter was found or not wasexamined.

Evaluation:

◯: Clear

Δ: Slight milky opaqueness or insoluble matter was found.

×: Milky opaqueness or the formation of insoluble matter was found.

TABLE 2 Composition and evaluation (parts by mass) Comparative ExampleExample 1 2 3 4 5 6 1 2 3 4 5 (Oil and fat composition) (Deteriorated)rapeseed oil 100 99 99 99 99 99 99 99 99 99 99 (shirasame-yu) a 1 b 1 c1 d 1 e 1 f 1 g 1 h 1 i 1 j 1 Height of foams (mm) 113 45 110 100 86 9037 30 25 18 15 Solubility ◯ Δ ◯ X ◯ X ◯ Δ ◯ ◯ ◯ Notes) A deterioratedrapeseed oil (shirashime-yu) was used in the tests for determining theheight of foams, and a fresh rapeseed oil (shirashime-yu) was used forthe evaluation of the solubility. Deteriorated rapeseed oil(shirashime-yu): An oil deteriorated by using fresh rapeseed oil(shirashime-yu) for deep-frying 10 pieces of potatoes, 12 pieces ofchicken and 10 pieces of breaded pork cutlets.

TABLE 3 Composition and evaluation (parts by mass) Comparative ExampleExample 7 8 9 10 11 12 6 7 8 9 10 (Oil and fat composition)(Deteriorated) sesame 100 95 99 94 99 94 salad oil (Deteriorated) MCT 55 5 (Deteriorated) MLCT 100 99 99 99 99 b 1 d 1 e 1 f 1 g 1 h 1 i 1 j 1Height of foams (mm) 115 130 127 114 120 95 36 37 29 25 17 Solubility ◯◯ ◯ ◯ ◯ X ◯ Δ ◯ ◯ ◯ Notes) A deteriorated sesame salad oil, deterioratedMCT and deteriorated MLCT were used for the tests for determining theheight of foams, and a fresh sesame salad oil, fresh MCT and fresh MLCTwere used for the evaluation of the solubility. MCT: Triglyceridescomposed of caprylic acid and capric acid (mass ratio: 75:25) as theconstituent fatty acids MLCT: An oil obtained by the transesterificationof rapeseed oil and MCT in a mass ratio of 8:2 Deteriorated sesame saladoil, deteriorated MCT and deteriorated MLCT: The oils each deterioratedby using it for deep-frying 10 pieces of potatoes, 12 pieces of chickenand 10 pieces of breaded pork cutlets.

Comparative Examples 13 to 15 and Examples 11 to 17

Comparative oil and fat compositions and the oil and fat compositions ofthe present invention shown in Table 4 were prepared and subjected to adeep-frying test.

(Deep-frying Test)

600 g of each of oil and fat compositions was fed into an electric homecooking fryer, and 6 deep-fried shrimps, 4 pieces of croquettes, 10pieces of deep-fried chicken and 10 pieces of breaded pork cutlets wereprepared therein at 180° C. The degree of foaming of the oil, emittingof smoke after the completion of the test and the taste of the friedfoods were evaluated.

(Determination of Foaming):

⊚: excellent

◯: ordinary foaming

Δ: strong foaming

×: violent foaming

(Evaluation of Taste)

As compared with rapeseed oil (shirashime-yu):

⊚: equivalent

Δ: The flavor and taste are a little different, but the difference isinsignificant.

×: The flavor and taste are different and the deep-fried food did nottaste good.

TABLE 4 Composition and evaluation (parts by mass) Comparative ExampleExample 13 14 15 11 12 13 14 15 16 17 (Oil and fat composition) Rapeseedoil (shirasame-yu) 85 97 98 Sesame salad oil 100 95 82 99 92 MCT 5 5 5MLCT 100 99.5 e 15 3 g 13 2 3 j 1 0.5 (Foaming) Deep-fried shrimps ◯ X ◯⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Croquettes ◯ X Δ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ ⊚ Deep-fried chicken Δ X Δ ⊚⊚ ◯ ⊚ ⊚ ⊚ ⊚ Breaded pork cutlets X X X ⊚ ⊚ ◯ ⊚ ◯ ◯ ⊚ Smoking ◯ Δ ◯ X Δ ◯◯ ◯ ◯ ◯ Flavor and taste ◯ ◯ ◯ X Δ ◯ ◯ ◯ ◯ ◯

Examples 18 and 19

Deep-frying tests were conducted by using MLCT containing 2% by mass (g)or 0.5% by mass (x) of polyglycerol fatty acid esters (Example 18) or 2%by mass (g) or 0.5% by mass (w) of polyglycerol fatty acid esters(Example 19). In both Examples 18 and 19, the cooking was possiblewithout any problem, and the cooked foods had excellent flavor andtaste. After keeping the oils at 0° C. for 2 weeks, both oils used inExamples 18 and 19 were transparent and clear, and no milky opaquenessor the formation of insoluble matter was found.

As described above in detail, the present invention relates to oil andfat compositions used as general-purpose cooking oils having a longdeep-frying life, which compositions have a controlled foaming in thecourse of the frying and also good cooking properties.

What is claimed is:
 1. An oil and fat composition exhibiting anantifoaming effect, which comprises: (i) at least 50% by mass oftriglycerides comprising fatty acids, wherein the fatty acids comprisefatty acids having 6 to 12 carbon atoms and fatty acids having 14 to 22carbon atoms in a mass ratio of 5:95 to 95:5; and (ii) 0.01 to 10% bymass of one or more polyglycerol fatty acid ester having an averagedegree of polymerization of 11 to 20 and an average degree ofsubstitution of 6 to 20, wherein the unsaturated fatty acid content offatty acids constituting the polyglycerol fatty acid ester is 50 to 100%by mass based on the total fatty acids constituting the polyglycerolfatty acid ester.
 2. The oil and fat composition according to claim 1,wherein the unsaturated fatty acid content of the fatty acidsconstituting the polyglycerol fatty acid ester is 70 to 100% by massbased on the total fatty acids constituting the polyglycerol fatty acidester.
 3. The oil and fat composition according to claim 1, whereinaliphatic carboxylic acids constituting the polyglycerol fatty acidester have 8 to 20 carbon atoms.
 4. A method of using the oil and fatcomposition according to claim 1, comprising including the oil and fatcomposition in an edible product.
 5. A method of using the oil and fatcomposition according to claim 2, comprising including the oil and fatcomposition in an edible product.
 6. A method of using the oil and fatcomposition according to claim 3, comprising including the oil and fatcomposition in an edible product.
 7. A method of cooking food whichcomprises heat-cooking food with the oil and fat composition of claim 1.8. A method of cooking food which comprises heat-cooking food with theoil and fat composition of claim
 2. 9. A method of cooking food whichcomprises heat-cooking food with the oil and fat composition of claim 3.